Thailand's interim prime minister has asked the country's electoral commission for an August 3 election, after the army declared martial law on Tuesday amid months of street protests.

Niwatthamrong Boonsongpaisan also said he would talk to the army chief General Prayut Chan-ocha "as soon as possible" to end the country's political crisis.

"If the [Electoral Commission] agrees, then next week we can issue a decree," Mr Niwatthamrong said.

Meanwhile, General Prayut will chair a meeting between representatives from all sides early on Wednesday afternoon.

A military spokeswoman says the meeting will be attended by top officials from the ruling and opposition parties, the Election Commission, the Senate and the heads of the pro and anti-government protest groups at 1:30pm local time.

However, the government views an early general election - which it would likely win - as the best way forward.

Last week, the commission called for national polls planned for July to be postponed due to the escalating political unrest.

General Prayut said the military had stepped in to restore order and build investor confidence, and warned that troops would take action against anyone who used weapons and harmed civilians.

"We ask all sides to come and talk to find a way out for the country," he told reporters after meeting directors of government agencies and other high-ranking officials.

Military officials said they were not interfering with the caretaker government, but ministers were not informed of the army's plan before an announcement on television at 3am local time on Tuesday.

General Prayut said martial law would be maintained until peace and order had been restored.

Australia's ambassador to Thailand James Wise says tourists should still travel to the country, but said visitors should avoid protest areas.

"Our advice is that people should still come to Thailand, exercise caution and the critical thing is to stay away from any sites where demonstrations are occurring where protestors are," he said.

Twenty-eight people have been killed and 700 injured since the anti-government protests began in November last year.

The crisis is the latest instalment of a near-decade-long power struggle between former telecoms tycoon Thaksin Shinawatra and the royalist establishment that has brought the country to the brink of recession and even raised fears of civil war.

Thailand has been stuck in political limbo since former prime minister Yingluck Shinawatra, Thaksin's younger sister, and nine of her ministers were dismissed earlier this month after a court found them guilty of abuse of power.

Election might be 'wishful thinking'

The ABC's South-East Asia correspondent Samantha Hawley told The World that "any thought of an election today might just be wishful thinking".

She said people hope there is a poll soon, but it is unclear when it will happen.

"The government has been pushing for an election the whole time. Of course they tried it in February. It failed. They then tried to set another election date in July," she said.

"Then the PM was removed from office. Now they are asking for a new election date and certainly we have no idea if that would actually proceed or be agreed to. It's very uncertain times here in Thailand.

"The nation is under martial law. The soldiers came out on the streets [on Tuesday] morning to make sure everyone knew that - that they know that the military is now in control of the streets around the country, particularly of course in Bangkok."

Army preventing marches, calls on media to watch broadcasts

Troops initially stopped some traffic from entering Bangkok, took up positions at intersections and secured television stations but life went on as normal in most of the city.

Both pro- and anti-government protesters are camped out at different places in the capital, and, to prevent clashes, the army has told them they have to stay put and cannot march.

The army also called on media not to broadcast material that would affect national security and ordered 10 satellite television channels, including both pro- and anti-government stations, to stop broadcasting.

The interim government said it welcomed the move to restore order and that it remained in office.

"The army's actions must be under the framework of the constitution," Mr Niwatthamrong said.

Martial law is a phantom coup: analyst

The army has played down fears of a coup, stressing that politicians must resolve the dispute.

But Human Rights Watch called the army's latest action a "de facto coup" while a political analyst said it was a "phantom coup".

"There was no consultation with the government and I think the military will slowly expand its powers and test the waters," Siam Intelligence Unit think-tank spokesman Kan Yuenyong said.

"For this to be a success the army needs to act like a neutral force and not be seen to side with the anti-government protesters. It needs to offer an election date and start a political reform process at the same time."

Martial law gives the military broad powers over civilian authorities, but a full coup would likely incur costs in terms of greater damage to investor confidence and US sanctions.

Meanwhile, Australia's Department of Foreign Affairs said its current travel advice for Australians in Thailand is to show a "high degree of caution".

The department urges them to avoid all protests, protest sites and political events, as it seeks further details about the situation in the capital.

"Thailand has Australia's goodwill and support as it tries to find ways to settle its political difficulties," DFAT said in a statement.

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